Fo-ti + Acetaminophen, Codeine, Doxylamine
Acetaminophen, Codeine, Doxylamine brand name: Mersyndol.
Acetaminophen, Codeine, Doxylamine falls into 3 drug categories that Fo-ti can interact with; the most serious is rated moderate. Theoretically, fo-ti may increase the levels and clinical effects of drugs metabolized by CYP2D6.
Read the full interaction reportFo-ti and Acetaminophen, Codeine, Doxylamine
These two interact in 3 distinct ways. Each one is explained separately below.
Why Are There 3 Interactions?
Fo-ti interacts with whole categories of medication. Acetaminophen, Codeine, Doxylamine falls into 3 of those categories, so it can interact with Fo-ti in 3 different ways. We’ve listed each one below — your overall risk is driven by the most serious of them (Moderate).
CYTOCHROME P450 2D6 (CYP2D6) SUBSTRATES
1 of 3Why this applies to Acetaminophen, Codeine, Doxylamine
Acetaminophen, Codeine, Doxylamine falls under CYTOCHROME P450 2D6 (CYP2D6) SUBSTRATES — the group Fo-ti interacts with.
Animal research suggests that fo-ti might inhibit CYP2D6. Additionally, an in vitro study suggests that the degree of CYP2D6 inhibition may depend on the type of fo-ti extract (i.e., the raw plant leads to greater inhibition than extensively processed extracts). However, this interaction has not been reported in humans.
Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.
Here's the wrinkle with Mersyndol: the codeine part is a prodrug. Your body has to use an enzyme called CYP2D6 to turn codeine into morphine, which is what actually relieves pain. Lab and animal studies hint that Fo-ti, especially the raw, less-processed root, may slow CYP2D6 down. If that enzyme is blocked, less codeine gets converted, so you might get weaker pain relief rather than more.
I want to keep this in perspective, though. This is based only on test-tube and animal work, and it hasn't actually been seen in people, so it's theoretical. The acetaminophen and doxylamine pieces aren't really the concern here. If you take both regularly, just give your pharmacist or doctor a quick heads-up so they can keep an eye on how well your pain is controlled.
- Zhang Y, Ding T, Diao T, Deng M, Chen S. Effects of Polygonum multiflorum on the activity of cytochrome P450 isoforms in rats. Pharmazie 2015;70(1):47-54. DOI
- Xing Y, Yu Q, Zhou L, et al. Cytochrome P450-mediated herb-drug interaction (HDI) of Polygonum multiflorum Thunb. based on pharmacokinetic studies and in vitro inhibition assays. Phytomedicine 2023;112:154710. PubMed
CYTOCHROME P450 1A2 (CYP1A2) SUBSTRATES
2 of 3Acetaminophen, Codeine, Doxylamine also falls under CYTOCHROME P450 1A2 (CYP1A2) SUBSTRATES.
In vitro research suggests that fo-ti might inhibit CYP1A2. Additionally, in vitro research suggests that the degree of CYP1A2 inhibition depends on the type of fo-ti extract (i.e., the raw plant leads to greater inhibition than extensively processed extracts). However, in an animal study, an aqueous extract of fo-ti inhibited CYP1A2 while an alcoholic extract of fo-ti induced CYP1A2. Induction or inhibition of CYP1A2 by fo-ti has not been reported in humans.
Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.
Here's the honest picture with Mersyndol (acetaminophen, codeine, and doxylamine) and Fo-ti. The concern on file is that Fo-ti may nudge an enzyme called CYP1A2 either up or down. For your medicine, none of the three main ingredients lean heavily on CYP1A2, so this isn't a primary pathway for clearing them. That makes any real-world effect uncertain.
The evidence here is also weak, coming only from lab and animal studies, with nothing seen in people. So I wouldn't be alarmed. That said, both Fo-ti and acetaminophen have been linked to liver strain, and combining the two could add stress on your liver, which is worth a quick chat with your pharmacist or doctor before pairing them.
- Unger M, Frank A. Simultaneous determination of the inhibitory potency of herbal extracts on the activity of six major cytochrome P450 enzymes using liquid chromatography/mass spectrometry and automated online extraction. Rapid Commun Mass Spectrom 2004;1 PubMed
- Zhang Y, Ding T, Diao T, Deng M, Chen S. Effects of Polygonum multiflorum on the activity of cytochrome P450 isoforms in rats. Pharmazie 2015;70(1):47-54. DOI
- Xing Y, Yu Q, Zhou L, et al. Cytochrome P450-mediated herb-drug interaction (HDI) of Polygonum multiflorum Thunb. based on pharmacokinetic studies and in vitro inhibition assays. Phytomedicine 2023;112:154710. PubMed
HEPATOTOXIC DRUGS
3 of 3Acetaminophen, Codeine, Doxylamine also falls under HEPATOTOXIC DRUGS.
Fo-ti has been linked to liver damage in many reports.
Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.
Here's the simple version: this combo product (Mersyndol) contains acetaminophen, and acetaminophen is hard on the liver if you take too much or stack it with other things that stress that organ. Fo-ti has been tied to a number of liver injury reports of its own. So the worry isn't a chemical clash in your bloodstream, it's two things leaning on the same organ at the same time.
To be fair, this is a theoretical concern backed mostly by scattered case reports, not strong studies. Still, watch for warning signs of liver trouble: yellowing skin or eyes, dark urine, belly pain on the upper right, unusual tiredness, or nausea. Before mixing them, check with your pharmacist or doctor, especially if you drink alcohol or take other acetaminophen products.
- Park GJ, Mann SP, Ngu MC. Acute hepatitis induced by Shou-Wu-Pian, a herbal product derived from Polygonum multiflorum. J Gastroenterol Hepatol 2001;16:115-7.
- But PP, Tomlinson B, Lee KL. Hepatitis related to the Chinese medicine Shou-wu-pian manufactured from Polygonum multiflorum. Vet Hum Toxicol 1996;38:280-2.
- UK Medicines and Healthcare Products Regulatory Agency. Polygonum multiflorum and liver reactions. April 2006. Available at: www.mhra.gov.uk/home/idcplg?IdcService= SS_GET_PAGE&useSecondary=true&ssDocName= CON2023590&ssTargetNodeId= 833 (Accessed 10 May 2
- Panis B, Wong DR, Hooymans PM, De Smet PA, Rosias PP. Recurrent toxic hepatitis in a Caucasian girl related to the use of Shou-Wu-Pian, a Chinese herbal preparation. J Pediatr Gastroenterol Nutr 2005;41:256-8. PubMed
- Mazzanti G, Battinelli L, Daniele C, et al. New case of acute hepatitis following the consumption of Shou Wu Pian, a Chinese herbal product derived from Polygonum multiflorum. Ann Intern Med 2004;140:E589-90.
- Cardenas A, Restrepo JC, Sierra F, Correa G. Acute hepatitis due to shen-min: a herbal product derived from Polygonum multiflorum. J Clin Gastroenterol 2006;40:629-32. PubMed
- Laird AR, Ramchandani N, deGoma EM, et al. Acute hepatitis associated with the use of an herbal supplement (Polygonum multiflorum) mimicking iron-overload syndrome. J Clin Gastroenterol 2008;42:861-2. PubMed
- Jung KA, Min HJ, Yoo SS, et al. Drug-Induced Liver Injury: Twenty Five Cases of Acute Hepatitis Following Ingestion of Polygonum multiflorum Thunb. Gut Liver 2011;5(4):493-9. PubMed
- Yuen, M. F., Tam, S., Fung, J., Wong, D. K., Wong, B. C., and Lai, C. L. Traditional Chinese medicine causing hepatotoxicity in patients with chronic hepatitis B infection: a 1-year prospective study. Aliment.Pharmacol.Ther 10-15-2006;24(8):1179-1186. PubMed
- Bae, S. H., Kim, D. H., Bae, Y. S., Lee, K. J., Kim, D. W., Yoon, J. B., Hong, J. H., and Kim, S. H. [Toxic hepatitis associated with Polygoni multiflori]. Korean J.Hepatol. 2010;16(2):182-186. PubMed
- Furukawa, M., Kasajima, S., Nakamura, Y., Shouzushima, M., Nagatani, N., Takinishi, A., Taguchi, A., Fujita, M., Niimi, A., Misaka, R., and Nagahara, H. Toxic hepatitis induced by show-wu-pian, a Chinese herbal preparation. Intern.Med. 2010;49(15):1537-1 PubMed
- Dong H, Slain D, Cheng J, Ma W, Liang W. Eighteen cases of liver injury following ingestion of Polygonum multiflorum. Complement Ther Med 2014;22(1):70-4. PubMed
- Lei X, Chen J, Ren J, et al. Liver damage associated with Polygonum multiflorum Thunb.: a systematic review of case reports and case series. Evid Based Complement Alternat Med 2015;2015:459749.
What These Ratings Mean
Every interaction above is graded three ways — here’s the key to each label.
Clinically significant. Avoid the combination, or use only under close professional supervision.
Usually worth avoiding or managing — may need monitoring, a dose change, or timing apart.
Generally not serious. Be aware of it and mention it to your pharmacist.
- LikelyWell-controlled human studies have demonstrated the likely existence of this interaction.
- ProbableInteraction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
- PossibleInteraction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.
- UnlikelyInteraction has been demonstrated in animal or in lab research but has been shown not to occur in humans.
- AHigh-quality meta-analysis (quantitative systematic review).
- BCase-control study.
- CConsensus.
- DAnecdotal evidence.
These ratings are for information only. Never start, stop, or otherwise change your therapy before speaking with your provider.
Fo-ti Also Interacts With Other Medications
Fo-ti has 1,256 moderate known drug interactions in our database — the Acetaminophen, Codeine, Doxylamine one above is among them. If you take anything else, check it against the full list below.
Check Another of Your Medications Against Fo-ti
We haven’t checked that one against Fo-ti yet — ask our pharmacists directly.
Covers the 2,830 medications we’ve checked against Fo-ti. Pick one to open its full report.
See Every Supplement That Interacts With Acetaminophen, Codeine, Doxylamine
This page covers Fo-ti only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Acetaminophen, Codeine, Doxylamine page lists 261 supplements it has a documented interaction with, worst first, each one explained.
The most serious there right now: 1,4-butanediol (major), Activated Charcoal (major), Asarabacca (major), Beer (major) and Gamma-hydroxybutyrate (ghb) (major).
By severity: 11 major · 208 moderate · 42 minor.
From our pharmacist’s overview on the Acetaminophen, Codeine, Doxylamine page
“Mersyndol pairs acetaminophen with codeine and doxylamine, two sedating drugs in one tablet, so I read its interaction list with genuine vigilance. Of the 261 supplements and herbs on file, the biggest hazard is anything else that slows the brain: 78 ingredients add sedation, and that group holds several of the 11 major-rated entries,…”
Reviewed by 2 · Jul 18, 2026
Open the Acetaminophen, Codeine, Doxylamine interaction page
Taking Fo-ti as Part of a Dietary Supplement Product? Check It for Interactions
We hold 976 real supplement products containing Fo-ti, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Fo-ti. Your product may carry other ingredients that interact with Acetaminophen, Codeine, Doxylamine too, on top of Fo-ti — and those would not show on this page. Find your product and we’ll check every ingredient on its label:
Where Fo-ti and Acetaminophen, Codeine, Doxylamine Sit Against Everything Else
Out of every supplement and medication people look up on HelloPharmacist, here is where these two land this week — and which way each has been moving.
#214 of 1,452 supplements looked up here in the last 7 days
#1,591 of 2,830 medications looked up here in the last 7 days
Position among everything looked up on this site, not a measure of how commonly either one is used or how important it is. A supplement can climb this list because of a news story. It counts every request to the page, automated ones included, and nothing here identifies anyone.
About Fo-ti
What is Fo-ti?
- Anti-aging and longevity
- Hair graying and hair loss
- General tonic for vitality
- Constipation
- High cholesterol
Fo-ti (He Shou Wu) is a root used in traditional Chinese medicine, often promoted for healthy aging and hair. High-quality human evidence for these benefits is limited, and processed Fo-ti has been linked to reports of liver injury, so caution and professional guidance are important.
Other Drugs & Fo-ti
Browse every other medication we’ve checked against Fo-ti — both the ones with a known interaction and the ones without. Select any drug for the full detail.
No drugs match “”.
1,256 interactions
- Diclofenac Sodium ›
- Diltiazem ›
- Theophylline ›
- Nifedipine ›
- Ibuprofen ›
- Aspirin ›
- Hydrocortisone ›
- Insulin (rdna) ›
- Naproxen ›
- Doxycycline ›
- Erythromycin ›
- Estradiol ›
- Minocycline ›
- Propranolol ›
- Tetracycline ›
- Lidocaine ›
- Amoxicillin ›
- Hydrochlorothiazide ›
- Norethindrone ›
- Testosterone ›
- Verapamil ›
- Fenofibrate ›
- Levonorgestrel ›
- Prednisone ›
- Quinidine ›
- Cyclosporine ›
- Dexamethasone ›
- Glyburide ›
- Insulin (pork) ›
- Methyltestosterone ›
- Triazolam ›
- Zopiclone ›
- Bupropion ›
- Ciprofloxacin ›
- Colchicine ›
- Fentanyl ›
- Flurbiprofen ›
- Isotretinoin ›
- Orphenadrine ›
- Oxybutynin ›
- Oxycodone ›
- Phenytoin ›
- Prednisolone ›
- Tacrolimus ›
- Temazepam ›
- Allopurinol ›
- Budesonide ›
- Carbamazepine ›
- Clindamycin ›
- Dextromethorphan ›
- Diclofenac Potassium ›
- Dipyridamole ›
- Doxorubicin ›
- Fluticasone ›
- Formoterol ›
- Indomethacin ›
- Insulin (human) ›
- Miconazole ›
- Morphine Sulfate ›
- Trimipramine ›
Showing 60 of 1,256 moderate interactions — see all 1,256 on the Fo-ti page.
No interaction 1,573 drugs checked — show the list
We also checked Fo-ti against these medications and found no known interaction in our sources. Open any page to confirm.
- Levothyroxine ›
- Methylphenidate ›
- Ivermectin ›
- Escitalopram ›
- Docusate ›
- Valacyclovir ›
- Hydroxyurea ›
- Sumatriptan ›
- Acyclovir ›
- Lisinopril ›
- Lamotrigine ›
- Gabapentin ›
- Pregabalin ›
- Azithromycin ›
- Methylene Blue ›
- Levothyroxine, Liothyronine ›
- Cyclopentolate ›
- Candesartan Cilexetil ›
- Cephalexin ›
- Roxithromycin ›
- Acetaminophen, Dextromethorphan, Doxylamine ›
- Pegunigalsidase Alfa-iwxj ›
- Daptomycin ›
- Hexobarbitone ›
- Levothyroxine Sodium ›
- Levetiracetam ›
- Dexmethylphenidate ›
- Factor 7a ›
- Carbidopa, Levodopa ›
- Thyroid Hormone ›
- Minoxidil ›
- Mitomycin ›
- Levodopa ›
- Ezetimibe ›
- Cefaclor ›
- Vancomycin ›
- Phenylephrine ›
- Hethylphenidate Hcl ›
- Phentermine, Topiramate ›
- Bentoquatam ›
- Dirithromycin ›
- Procainamide ›
- Hydroxychloroquine ›
- Azelaic Acid ›
- Dextrothyroxine ›
- Triptorelin ›
- Lomustine ›
- Tocainide ›
- Pentobarbitone ›
- Pizotifen ›
- Succimer ›
- Rocuronium ›
- Mitomycin C ›
- Telmisartan ›
- Lorazepam ›
- Chenodiol ›
- Desflurane ›
- Metronidazole ›
- Famotidine ›
- Caspofungin ›
Showing the 60 most looked-up of 1,573 medications checked with no known interaction — see the full Fo-ti list.
Sources & How We Checked
Interaction details are evidence-graded and sourced from the Natural Medicines database. The medication overview comes from MedlinePlus.
- Natural Medicines (Therapeutic Research Center) — Evidence-graded clinical reference for vitamins, herbs and supplements — the basis for our interaction data.
- MedlinePlus, U.S. National Library of Medicine — NIH consumer drug information, used for the medication overviews.
- NIH Dietary Supplement Label Database (DSLD) — Official supplement product labels.
Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.
Parts of this content are provided by the Therapeutic Research Center, LLC.
DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.
© 2021 Therapeutic Research Center, LLC
Acetaminophen, Codeine, Doxylamine Is Linked to Lower Levels of One Nutrient
Natural Medicines records Acetaminophen, Codeine, Doxylamine as a medicine that can lower these. This is not an interaction with Fo-ti — it is a separate effect of the medicine, and it is a reason some people are advised to supplement rather than to avoid one:
Read the full Acetaminophen, Codeine, Doxylamine nutrient depletion report ›
Depletion records come from the licensed Natural Medicines database. Do not start a supplement on the strength of this page — ask your pharmacist or doctor whether it applies to you.
Taking Fo-ti and Acetaminophen, Codeine, Doxylamine Together: Common Questions
Can you take Fo-ti with Acetaminophen, Codeine, Doxylamine?
Why are there 3 interactions listed for Fo-ti and Acetaminophen, Codeine, Doxylamine?
How serious is the Fo-ti and Acetaminophen, Codeine, Doxylamine interaction?
Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy
Still Have a Question About Acetaminophen, Codeine, Doxylamine and Fo-ti?
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This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.